https://gcc.gnu.org/bugzilla/show_bug.cgi?id=43892
--- Comment #31 from Segher Boessenkool <segher at gcc dot gnu.org> --- Performing a jump based on the carry bit is not something we can easily do (there are no simple insns for it, and those sequences that will do the trick are expensive). But I'll look at that, thanks for the hint! At least in the __builtin_add_overflow case most of it will be ootimised away :-)
